1. Field of the Invention
The present invention relates to the field of medical imaging. More particularly, embodiments of the invention relate to methods, systems, and devices for imaging, including for tomography-based applications.
2. Description of the Related Art
Existing CT schemes take projection data from an x-ray source being scanned along a trajectory and reconstruct an image from these data that are essentially line integrals through an object. In real-world applications, however, higher temporal resolution has been constantly pursued, such as for dynamic medical CT, and micro- and nano-CT. The multi-source scanning mode is well known to improve temporal resolution but the data acquisition and field of view are seriously restricted to avoid overlapped projections, such as in the case of the classic dynamic spatial reconstructor (DSA). Needed are methods of reconstructing an image using overlapped projection data, resulting in faster data acquisition without reducing image quality.
Small animal imaging is critically important in this post-genomic era. Currently, major efforts are being made in the fields of systems biology and medicine to link genomic and epigenetic features with complicated biological interactions such as phenotypic expression. Small animals, particularly genetically engineered mice, are often used as models of almost all human diseases. Over the past decade, there has been explosive growth in development of micro-imaging technologies to study small animals with emphasis on mice. At present, most all major biomedical research institutions and companies extensively use micro-imaging tools, including x-ray micro-CT, micro resonance imaging (micro-MRI), micro single photon emission computed tomography (micro-SPECT), micro positron emission tomography (micro-PET), ultrasound (US) and optical scanners.
Unique merits of x-ray micro-CT are evident relative to other micro-imaging modalities in the context of small animal imaging. In terms of imaging speed and cost-effectiveness, micro-CT is superior to magnetic resonance microscopy (MRM) and micro-MRI. Micro-CT captures much finer features than micro-PET and micro-SPECT, which is needed for accurate functional and molecular imaging. Micro-CT allows significantly deeper penetration than optical imaging, and much less artifacts than US. Two major limitations of current micro-CT techniques, however, are insufficient contrast resolution and high radiation dose.
Thus a need exists for spectrally-resolved photon-counting based methods, systems, and devices, which are capable of bright and colorful CT images for anatomical, functional, cellular and molecular imaging. Such imaging modalities are expected to lead to major healthcare benefits for diagnosis and treatment of cancers, cardiovascular diseases, and other pathologies.
Bioluminescence tomography (BLT) can be used to localize and quantify bioluminescent sources in a small living animal. Advancing planar bioluminescent imaging to the tomographic imaging framework, BLT helps detect gene expression, monitor therapies and facilitate drug development, among many other applications.
More particularly, BLT is used to reconstruct the bioluminescence source from the boundary measurement based on a physical model in which the optical parameters are unknown. The optical parameters and source, however, cannot be simultaneously reconstructed only from boundary measurement. Accordingly, what is needed is a modality fusion imaging methodology that can be used to recover the optical parameters using the photoacoustic imaging modality for a better forward modeling so that BLT reconstruction quality can be improved.
A major barrier to advancing tissue engineering research is our inability to monitor dynamic biological processes in a minimally invasive real-time fashion, which makes control and optimization extremely difficult. Current methods to assess tissue regeneration, such as histological and physiological analyses, are highly invasive and require destruction of the newly formed tissue, creating a fundamental knowledge discrepancy between cellular processes and whole organ biology. Thus, what is needed are minimally-invasive approaches for performing tomography-based procedures deep within tissue.
Further, many promising optical molecular imaging modalities, such as bioluminescence tomography, have a limited ability to detect deeply embedded optical molecular probes. Thus, what are needed are systems, methods, and devices using a sparsity-regularized computational optical biopsy (SCOB) approach for locating and quantifying the bioluminescent probes regardless of the source depth.